The San Francisco Civic Center and United Nations Plaza were evacuated Saturday due to a standoff with an armed man that lasted roughly six hours, police said. Christie Smith reports. (Published Saturday, Sept. 24, 2016)

The San Francisco Civic Center and United Nations Plaza were evacuated Saturday due to a six-hour standoff with an armed man, who it turned out was carrying an airsoft gun, police said.

The man, who surrendered peacefully around 6 p.m., was initially reported to be carrying a semi-automatic handgun that he did not fire, according to police spokesman Carlos Manfredi. The man had threatened to "use the gun on officers and on himself," Manfredi said.

Fire officials later clarified that the man was carrying an airsoft or replica gun.

The man, who Manfredi said is a San Francisco resident in his 40s, called 911 after 12 p.m. and reported that he had a weapon and was standing in the center of the plaza. Police were "assuming" the gun is "loaded," Manfredi said.

Police evacuated people in a two-block radius and secured the perimeter, Manfredi said, but initial attempts to talk to the man were not successful so officers "took a step back."

Crisis hostage negotiators were then called in and the SWAT team was also on scene, according to Manfredi. Negotiators were seeking a "good dialogue" with the man so they could better understand "what's going on," he said.

"As long as we have time to talk to this person, we have hope," Manfredi said.

Police believed the man may be suicidal because of some of the things he said, like wanting "to end his life" and "take out other people," Manfredi said.

"We don't want that to happen," he said.

The surrounding roads were blocked to traffic, and pedestrians and motorists were sked to avoid the area. The Federal Aviation Administration also instated temporary flight restrictions for two nautical miles around the Civic Center to ensure the safety of all involved.

Police did not believe the standoff is terror-related, said Manfredi, who could not comment on whether the man is lucid or under the influence of any drugs.

Code 4. Suspect surrendered peacefully without further incident. Good work Crisis Negotiators & everyone out at the scene. pic.twitter.com/n7UvLeXfj0